CVE-2026-43037
Description
A flaw was found in the Linux kernel's IPv6 tunnel implementation. A remote attacker could exploit this flaw by sending malicious ICMPv6 error messages to cause a stack-based buffer overflow in the kernel's IPv4-over-IPv6 tunnel error handling code. This could result in a kernel crash (denial of service) or potentially allow arbitrary code execution with kernel privileges.
Statement
This Critical flaw in the Linux kernel's IPv6 tunneling error handling can lead to a stack buffer overflow. An unauthenticated remote attacker could exploit this by sending specially crafted network packets, potentially resulting in a denial of service or information disclosure on affected Red Hat Enterprise Linux systems.
Mitigation
Mitigation for this issue is to skip loading the affected module `ip6_tunnel` onto the system till we have a fix available, this can be done by a blacklist mechanism, this will ensure the driver is not loaded at the boot time.
How do I blacklist a kernel module to prevent it from loading automatically?
https://access.redhat.com/solutions/41278
We may also want to detection and monitoring an affected system as below:
Monitor for exploitation attempts:
# Enable kernel audit for IPv6 tunnel operations
auditctl -a always,exit -F arch=b64 -S socket -F a0=10 -F a1=3 -k ipv6_tunnel
# Monitor system logs for kernel panics/crashes
journalctl -k -p err -f | grep -i "ip6_tunnel\|icmp\|stack"
Common Vulnerability Scoring System (CVSS) Score Details
Info alert:Important note
CVSS scores for open source components depend on vendor-specific factors (e.g. version or build chain). Therefore, Red Hat's score and impact rating can be different from NVD and other vendors. Red Hat remains the authoritative CVE Naming Authority (CNA) source for its products and services (see Red Hat classifications).
CVSS v3 Score Breakdown
| Red Hat | NVD | cve.org | |
|---|---|---|---|
| Base Score | 8.8 | N/A | 8.8 |
| Attack Vector | Network | N/A | Network |
| Attack Complexity | Low | N/A | Low |
| Privileges Required | Low | N/A | Low |
| User Interaction | None | N/A | None |
| Scope | Unchanged | N/A | Unchanged |
| Confidentiality | High | N/A | High |
| Integrity Impact | High | N/A | High |
| Availability Impact | High | N/A | High |
Vector
Red Hat: CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
cve.org: CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
Understanding the Weakness (CWE)
Availability,Integrity,Confidentiality
Technical Impact: Read Memory; Modify Memory; Execute Unauthorized Code or Commands; DoS: Crash, Exit, or Restart
When a memory buffer is accessed using the wrong type, it could read or write memory out of the bounds of the buffer, if the allocated buffer is smaller than the type that the code is attempting to access, leading to a crash and possibly code execution.
Frequently Asked Questions
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